RFID tag circuits, tags, and methods are provided for using alternative memory lock bits. A pointer in tag memory is configured to point to one or the other of the alternative lock bits associated with a section of the memory for performing a function in response to a reader command. Upon receiving the reader command, the tag first checks the pointer and performs the function based on which lock bit(s) is selected.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An RFID tag circuit, comprising: a memory, the memory having a first location for storing a first lock bit, a second location for storing a second lock bit, wherein the first lock bit and the second lock bit have different values, a third location for storing a pointer configured to point to one of the first lock bit and the second lock bit, wherein the pointer is configurable to stop pointing to the first lock bit and start pointing instead to the second lock bit responsive to the tag circuit receiving a partial-kill command, and a section having an operable functionality if the pointed to one of the first and the second lock bits has a first value, but lacking the operable functionality if the pointed to one of the first and the second lock bits has a second value; and a modulator able to cause a reply to be backscattered regardless of whether the pointer is configured to point to the first lock bit or to the second lock bit.
2. The circuit of claim 1 , in which the operable functionality includes reading the memory section.
3. The circuit of claim 1 , in which the operable functionality includes writing to the memory section.
4. The circuit of claim 1 , in which the operable functionality includes read-locking the memory section.
5. The circuit of claim 1 , in which the operable functionality includes write-locking the memory section.
6. The circuit of claim 1 , in which the pointer is determined at tag power-up.
7. The circuit of claim 1 , in which once the pointer has been configured by the partial-kill command, it cannot be configured to start pointing back to the first lock bit.
8. The circuit of claim 1 , in which the pointer becomes configured by acquiring a value that is carried as a payload of the partial-kill command.
9. A method for an RFID tag, comprising: receiving a first command; responsive to the first command, operating a functionality of a section of a memory of the RFID tag if a pointed to one of a first lock bit and a second lock bits stored in the memory has a first value, but not operating the functionality if the pointed to one of the first and second lock bits has a second value, the pointing by a pointer configured to point to one of the first and second lock bits, wherein the first lock bit and the second lock bit have different values and the pointer is configurable to stop pointing to the first lock bit and start pointing instead to the second lock bit responsive to the tag circuit receiving a partial-kill command; and backscattering a reply regardless of whether the functionality was operated or not.
10. The method of claim 9 , in which the reply is backscattered in response to the first command.
11. The method of claim 9 , further comprising: losing power; receiving power again; powering up responsive to receiving power again; then receiving a second command; and in which the reply is backscattered in response to the second command, but no reply is backscattered in response to the first command.
12. The method of claim 9 , in which the operable functionality includes reading the memory section.
13. The method of claim 9 , in which the operable functionality includes writing to the memory section.
14. The method of claim 9 , in which the operable functionality includes read-locking the memory section.
15. The method of claim 9 , in which the operable functionality includes write-locking the memory section.
16. The method of claim 9 , further comprising: powering up before receiving the first command, and in which the pointer is looked up responsive to powering up.
17. The method of claim 9 , in which once the pointer has been configured by the partial-kill command, it cannot be configured to start pointing back to the first lock bit.
18. The method of claim 9 , in which the pointer becomes configured by acquiring a value that is carried as a payload of the partial-kill command.
19. An RFID tag, comprising: an antenna; a memory, the memory having a first location for storing a first lock bit, a second location for storing a second lock bit, wherein the first lock bit and the second lock bit have different values, a third location for storing a pointer configured to point to one of the first lock bit and the second lock bit, wherein the pointer is configurable to stop pointing to the first lock bit and start pointing instead to the second lock bit responsive to the tag receiving a partial-kill command, and a section having an operable functionality if the pointed to one of the first and the second lock bits has a first value, but lacking the operable functionality if the pointed to one of the first and the second lock bits has a second value; and a modulator able to cause the antenna to backscatter a reply regardless of whether the pointer is configured to point to the first lock bit or to the second lock bit.
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October 16, 2007
January 18, 2011
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